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  <title>Adds a negative arc</title>

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</div><hr /><div id="cairocontext.arcnegative" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">CairoContext::arcNegative</h1>
  <h1 class="refname">cairo_arc_negative</h1>
  <p class="verinfo">(PECL cairo &gt;= 0.1.0)</p><p class="refpurpose"><span class="refname">CairoContext::arcNegative</span> -- <span class="refname">cairo_arc_negative</span> &mdash; <span class="dc-title">Adds a negative arc</span></p>

 </div>

 <div class="refsect1 description" id="refsect1-cairocontext.arcnegative-description">
  <h3 class="title">说明</h3>
  <p class="para">面向对象风格 (method):</p>
   <div class="methodsynopsis dc-description">
   <span class="modifier">public</span> <span class="type"><span class="type void">void</span></span> <span class="methodname"><strong>CairoContext::arcNegative</strong></span>
    ( <span class="methodparam"><span class="type">float</span> <code class="parameter">$x</code></span>
   , <span class="methodparam"><span class="type">float</span> <code class="parameter">$y</code></span>
   , <span class="methodparam"><span class="type">float</span> <code class="parameter">$radius</code></span>
   , <span class="methodparam"><span class="type">float</span> <code class="parameter">$angle1</code></span>
   , <span class="methodparam"><span class="type">float</span> <code class="parameter">$angle2</code></span>
    )</div>

  <p class="para rdfs-comment">过程化风格:</p>
  <div class="methodsynopsis dc-description">
   <span class="type"><span class="type void">void</span></span> <span class="methodname"><strong>cairo_arc_negative</strong></span>
    ( <span class="methodparam"><span class="type"><a href="class.cairocontext.html" class="type CairoContext">CairoContext</a></span> <code class="parameter">$context</code></span>
   , <span class="methodparam"><span class="type">float</span> <code class="parameter">$x</code></span>
   , <span class="methodparam"><span class="type">float</span> <code class="parameter">$y</code></span>
   , <span class="methodparam"><span class="type">float</span> <code class="parameter">$radius</code></span>
   , <span class="methodparam"><span class="type">float</span> <code class="parameter">$angle1</code></span>
   , <span class="methodparam"><span class="type">float</span> <code class="parameter">$angle2</code></span>
   )</div>

  <p class="para rdfs-comment">
   Adds a circular arc of the given <em><code class="parameter">radius</code></em> to the current path.
   The arc is centered at (<em><code class="parameter">x</code></em>, <em><code class="parameter">y</code></em>), begins at
   <em><code class="parameter">angle1</code></em> and proceeds in the direction of decreasing angles to end at
   <em><code class="parameter">angle2</code></em>. If <em><code class="parameter">angle2</code></em> is greater than
   <em><code class="parameter">angle1</code></em> it will be progressively decreased by 2*M_PI until it is less than
   <em><code class="parameter">angle1</code></em>.

    See <span class="methodname"><a href="cairocontext.arc.html" class="methodname">CairoContext::arc()</a></span> or <span class="function"><a href="cairocontext.arc.html" class="function">cairo_arc()</a></span> for more details.
    This function differs only in the direction of the arc between the two angles.
  </p>
 
 </div>


 <div class="refsect1 parameters" id="refsect1-cairocontext.arcnegative-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<em><code class="parameter">context</code></em></dt>

     <dd>

      <p class="para">
       A valid CairoContext object
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">x</code></em></dt>

     <dd>

      <p class="para">
       double x position
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">y</code></em></dt>

     <dd>

      <p class="para">
       double y position
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">radius</code></em></dt>

     <dd>

      <p class="para">
       The radius of the desired negative arc
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">angle1</code></em></dt>

     <dd>

      <p class="para">
       Start angle of the arc
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">angle2</code></em></dt>

     <dd>

      <p class="para">
       End angle of the arc
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-cairocontext.arcnegative-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   没有返回值。
  </p>
 </div>


 <div class="refsect1 examples" id="refsect1-cairocontext.arcnegative-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-2785">
    <p><strong>Example #1 面向对象风格</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br />$s&nbsp;</span><span style="color: #007700">=&nbsp;new&nbsp;</span><span style="color: #0000BB">CairoImageSurface</span><span style="color: #007700">(</span><span style="color: #0000BB">CairoFormat</span><span style="color: #007700">::</span><span style="color: #0000BB">ARGB32</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">100</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">100</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$c&nbsp;</span><span style="color: #007700">=&nbsp;new&nbsp;</span><span style="color: #0000BB">CairoContext</span><span style="color: #007700">(</span><span style="color: #0000BB">$s</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$c</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">setSourceRgb</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$c</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">paint</span><span style="color: #007700">();<br /><br /></span><span style="color: #0000BB">$c</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">setLineWidth</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$c</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">setSourceRgb</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /><br />for&nbsp;(</span><span style="color: #0000BB">$r&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">50</span><span style="color: #007700">;&nbsp;</span><span style="color: #0000BB">$r&nbsp;</span><span style="color: #007700">&gt;&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">;&nbsp;</span><span style="color: #0000BB">$r&nbsp;</span><span style="color: #007700">-=&nbsp;</span><span style="color: #0000BB">10</span><span style="color: #007700">)&nbsp;{<br />&nbsp;</span><span style="color: #0000BB">$c</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">arcNegative</span><span style="color: #007700">(</span><span style="color: #0000BB">50</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">50</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$r</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">2&nbsp;</span><span style="color: #007700">*&nbsp;</span><span style="color: #0000BB">M_PI</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">);<br />&nbsp;</span><span style="color: #0000BB">$c</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">stroke</span><span style="color: #007700">();<br />&nbsp;</span><span style="color: #0000BB">$c</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">fill</span><span style="color: #007700">();<br />}<br /><br /></span><span style="color: #0000BB">$s</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">writeToPng</span><span style="color: #007700">(</span><span style="color: #0000BB">dirname</span><span style="color: #007700">(</span><span style="color: #0000BB">__FILE__</span><span style="color: #007700">)&nbsp;.&nbsp;</span><span style="color: #DD0000">'/CairoContext__arcNegative.png'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
     </div>

   </div>
  </p>
  <p class="para">
   <div class="example" id="example-2786">
    <p><strong>Example #2 过程化风格</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br />$s&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">cairo_image_surface_create</span><span style="color: #007700">(</span><span style="color: #0000BB">CAIRO_SURFACE_TYPE_IMAGE</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">100</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">100</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$c&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">cairo_create</span><span style="color: #007700">(</span><span style="color: #0000BB">$s</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">cairo_set_source_rgb</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">cairo_paint</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">cairo_set_source_rgb</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">cairo_set_line_width</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /><br />for&nbsp;(</span><span style="color: #0000BB">$r&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">50</span><span style="color: #007700">;&nbsp;</span><span style="color: #0000BB">$r&nbsp;</span><span style="color: #007700">&gt;&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">;&nbsp;</span><span style="color: #0000BB">$r&nbsp;</span><span style="color: #007700">-=&nbsp;</span><span style="color: #0000BB">10</span><span style="color: #007700">)&nbsp;{<br />&nbsp;</span><span style="color: #0000BB">cairo_arc_negative</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">50</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">50</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$r</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">2&nbsp;</span><span style="color: #007700">*&nbsp;</span><span style="color: #0000BB">M_PI</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">);<br />&nbsp;</span><span style="color: #0000BB">cairo_stroke</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br />&nbsp;</span><span style="color: #0000BB">cairo_fill</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #0000BB">cairo_surface_write_to_png</span><span style="color: #007700">(</span><span style="color: #0000BB">$s</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">dirname</span><span style="color: #007700">(</span><span style="color: #0000BB">__FILE__</span><span style="color: #007700">)&nbsp;.&nbsp;</span><span style="color: #DD0000">'/cairo_arc_negative.png'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
     </div>

   </div>
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-cairocontext.arcnegative-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="methodname"><a href="cairocontext.arc.html" class="methodname" rel="rdfs-seeAlso">CairoContext::arc()</a> - Adds a circular arc</span></li>
   </ul>
  </p>
 </div>


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